12 ❙ EggIndustry
Pullet coccidiosis
vaccination is not
a one-time event
For long-lived poultry like layers and
breeders, a coccidiosis vaccine provides
the most economical form of protection.
JERRY DREYER
Coccidiosis is a parasitic disease
that requires continued exposure
to the Eimeria vaccine oocysts (a
stage in the coccidia life cycle) to
establish long-term protection. Dr.
Linnea Newman, global poultry
technical service director, Merck
Animal Health, says the most
common misunderstanding when
starting a layer pullet coccidiosis
vaccination program is an expectation of fast immunity.
"Most viral and bacterial disease vaccines are very successful
in initiating an immune response
within three to seven days after
being properly administered.
However, coccidiosis vaccination
requires up to four to five weeks
of oocyst cycling to stimulate immunity," said Newman.
Consequently, to successfully
immunize the flock, ongoing management practices in the pullet
house require careful attention to
relative humidity, proper manage-
ment of litter and/or cage paper to
allow cycling of vaccine oocysts
and monitoring of oocyst counts.
Oocyst cycling
The initial vaccination administers a controlled number of live
sporulated oocysts, which stimulate a primarily cellular immune
response in the intestinal tract.
These oocysts continue reproducing in the gut and eventually are
shed in the feces. It's important
for pullets to have access to the
feces where oocysts sporulate to
continue the immunization process. As birds ingest oocysts, the
coccidia reproductive life cycle
begins anew and the bird responds
with an even higher level of immunity.
The Eimeria reproductive life
cycle takes four to seven days, and
chickens require two to five cycles
to develop needed immunity (both
time periods vary by coccidia
species). Consequently, a successful immunization requires proper
initial vaccination as well as continued consumption of oocysts for
up to five weeks. After that time,
the flock should be able to resist
a coccidiosis challenge, assuming
an ongoing exposure to oocysts
remains through the production
period.
Vaccination process starts
in the hatchery
Most layer pullets are vaccinated in the hatchery by spray.
The vaccine is generally ingested
as chicks respond to the colored
vaccine solution by preening
themselves.
When using coarse spray administration, vaccine management
is extremely important to ensure
oocysts are constantly agitated
to prevent settling in the bottom
of the diluent container. Another
spray delivery method utilizes a
www.WATTAgNet.com ❙ April 2018